1. Field of the Invention
The invention relates to a method for connection of an optical element to a mount structure, a use of the optical element connected to the mount structure by means of the method, an arrangement comprising an optical element and a mount structure connected to the optical element, and a projection objective for microlithography comprising such an arrangement.
2. Description of the Related Art
U.S. Pat. No. 5,991,101 describes the connection of a lens to a holder by means of soldering.
U.S. Pat. No. 6,108,144 reveals a method for welding a large optical component to a metallic mount.
Further possibilities for connection of optical elements to mount structures are described in U.S. Pat. No. 6,229,657 B1 or U.S. Pat. No. 6,392,284 B1.
Furthermore, the combination of wringing with adhesive bonding is known from the general prior art.
If the resolution of a lithography objective equipped with a plurality of optical elements is intended to be improved, then one possibility consists in inserting a so-called immersion medium between the last optical element and the wafer to be exposed. The numerical aperture can be increased to a value of >1.0 in this way. The immersion medium, for example water, is usually present at the connection of the terminating element to a mount structure in such a case. Said immersion medium may attack the connection between the optical element and the mount structure and damage it in this way. Said damage may proceed to such an extent that the immersion medium can penetrate into the interior of the lithography objective.